The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Internal combustion engines generally require the use of a crankshaft to convert linear motion to rotational motion. Several surfaces of the crankshaft having various functions require machining to ensure proper operation of the crankshaft. Typically, some of the machining processes require spinning the crankshaft about a longitudinal axis that defines the main bearing journal axis of the crankshaft, while at the same time utilizing rotary grinding wheels to machine several various surfaces. This process is known as machine grinding.
During machine grinding, extreme heat and aggressive stock removal may alter micro structure and base metal hardness, creating slight dimensional and surface imperfections such as smeared peaks, waviness and chatter. A superfinishing process may be subsequently performed to improve surface finish and workpiece geometry by removing the amorphous layer formed during the grinding process.
A typical superfinishing process may be performed by using an abrasive tape or an abrasive stone. Abrasive tape finishing is more commonly used. Both tape finishing and stone finishing systems employ a series of mechanical clamping arms that must be positioned axially in line with the journals to be finished. With either system, the stone or the tape is clamped against the journals and remains stationary as the crankshaft rotates.
Performing the superfinishing process requires changing over from the grinding machine to the superfinishing system, positioning the various clamping arms of the superfinishing system, and positioning the tooling (stone or tape) relative to the journals of the crankshaft. Therefore, the typical method for grinding and finishing the crankshaft is complicated, time-consuming, and expensive.
This disclosure is directed to improving processes related to grinding and finishing journals and crankshafts.